Light pipe is used in two main ways. In an end-light application the light pipe is optimized to carry light along its length, and transmit it at the output face of the light pipe. In a side light application the light is extracted out the side of the light pipe and provides illumination along its length. Often, light extracted from the side of a light pipe over the full 360 degrees about the light pipe axis is undesirable because a reflector would be needed to redirect a significant portion of the light towards the intended area to be illuminated. Some of the redirected light impinges on the light pipe and may be either absorbed into the light pipe so as to reduce side-light output, or is scattered into unintended directions. This is the same drawback associated with fluorescent lighting and results in an inefficient fixture for delivering light onto the desired surface.
It would be desirable to eliminate the inefficient fixture and reflector combination for use with a light pipe by extracting the light only in the desired direction, towards a target area to be illuminated.
Alternatively, in a second embodiment of the invention, with a light pipe lacking a fluoropolymer cladding, it would be desirable to provide novel ways of extracting the light from the side of the light pipe.